1
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Ewart KM, Ho SYW, Chowdhury AA, Jaya FR, Kinjo Y, Bennett J, Bourguignon T, Rose HA, Lo N. Pervasive relaxed selection in termite genomes. Proc Biol Sci 2024; 291:20232439. [PMID: 38772424 DOI: 10.1098/rspb.2023.2439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 05/02/2024] [Indexed: 05/23/2024] Open
Abstract
Genetic changes that enabled the evolution of eusociality have long captivated biologists. More recently, attention has focussed on the consequences of eusociality on genome evolution. Studies have reported higher molecular evolutionary rates in eusocial hymenopteran insects compared with their solitary relatives. To investigate the genomic consequences of eusociality in termites, we analysed nine genomes, including newly sequenced genomes from three non-eusocial cockroaches. Using a phylogenomic approach, we found that termite genomes have experienced lower rates of synonymous substitutions than those of cockroaches, possibly as a result of longer generation times. We identified higher rates of non-synonymous substitutions in termite genomes than in cockroach genomes, and identified pervasive relaxed selection in the former (24-31% of the genes analysed) compared with the latter (2-4%). We infer that this is due to reductions in effective population size, rather than gene-specific effects (e.g. indirect selection of caste-biased genes). We found no obvious signature of increased genetic load in termites, and postulate efficient purging of deleterious alleles at the colony level. Additionally, we identified genomic adaptations that may underpin caste differentiation, such as genes involved in post-translational modifications. Our results provide insights into the evolution of termites and the genomic consequences of eusociality more broadly.
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Affiliation(s)
- Kyle M Ewart
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Simon Y W Ho
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Al-Aabid Chowdhury
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Frederick R Jaya
- Ecology & Evolution, Research School of Biology, Australian National University, Acton, Australian Capital Territory, Australia
| | - Yukihiro Kinjo
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- Okinawa International University, Okinawa, Japan
| | - Juno Bennett
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Thomas Bourguignon
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Harley A Rose
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Nathan Lo
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
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2
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Steward RA, Pruisscher P, Roberts KT, Wheat CW. Genetic constraints in genes exhibiting splicing plasticity in facultative diapause. Heredity (Edinb) 2024; 132:142-155. [PMID: 38291272 PMCID: PMC10923799 DOI: 10.1038/s41437-024-00669-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 12/28/2023] [Accepted: 01/03/2024] [Indexed: 02/01/2024] Open
Abstract
Phenotypic plasticity is produced and maintained by processes regulating the transcriptome. While differential gene expression is among the most important of these processes, relatively little is known about other sources of transcriptional variation. Previous work suggests that alternative splicing plays an extensive and functionally unique role in transcriptional plasticity, though plastically spliced genes may be more constrained than the remainder of expressed genes. In this study, we explore the relationship between expression and splicing plasticity, along with the genetic diversity in those genes, in an ecologically consequential polyphenism: facultative diapause. Using 96 samples spread over two tissues and 10 timepoints, we compare the extent of differential splicing and expression between diapausing and direct developing pupae of the butterfly Pieris napi. Splicing differs strongly between diapausing and direct developing trajectories but alters a smaller and functionally unique set of genes compared to differential expression. We further test the hypothesis that among these expressed loci, plastically spliced genes are likely to experience the strongest purifying selection to maintain seasonally plastic phenotypes. Genes with unique transcriptional changes through diapause consistently had the lowest nucleotide diversity, and this effect was consistently stronger among genes that were differentially spliced compared to those with just differential expression through diapause. Further, the strength of negative selection was higher in the population expressing diapause every generation. Our results suggest that maintenance of the molecular mechanisms involved in diapause progression, including post-transcriptional modifications, are highly conserved and likely to experience genetic constraints, especially in northern populations of P. napi.
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Affiliation(s)
- Rachel A Steward
- Zoology Department, Stockholm University, Stockholm, Sweden.
- Biology Department, Lund University, Lund, Sweden.
| | - Peter Pruisscher
- Zoology Department, Stockholm University, Stockholm, Sweden
- Science for Life Laboratory, Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
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3
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Mikhailova AA, Rinke S, Harrison MC. Genomic signatures of eusocial evolution in insects. CURRENT OPINION IN INSECT SCIENCE 2024; 61:101136. [PMID: 37922983 DOI: 10.1016/j.cois.2023.101136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/27/2023] [Accepted: 10/28/2023] [Indexed: 11/07/2023]
Abstract
The genomes of eusocial insects allow the production and regulation of highly distinct phenotypes, largely independent of genotype. Although rare, eusociality has evolved convergently in at least three insect orders (Hymenoptera, Blattodea and Coleoptera). Despite such disparate origins, eusocial phenotypes show remarkable similarity, exhibiting long-lived reproductives and short-lived sterile workers and soldiers. In this article, we review current knowledge on genomic signatures of eusocial evolution. We confirm that especially an increased regulatory complexity and the adaptive evolution of chemical communication are common to several origins of eusociality. Furthermore, colony life itself can shape genomes of divergent taxa in a similar manner. Future research should be geared towards generating more high-quality genomic resources, especially in hitherto understudied clades, such as ambrosia beetles and termites. The application of more sophisticated tools such as machine learning techniques may allow the detection of more subtle convergent genomic footprints of eusociality.
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Affiliation(s)
- Alina A Mikhailova
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany
| | - Sarah Rinke
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany
| | - Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany.
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4
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Differential Selection on Caste-Associated Genes in a Subterranean Termite. INSECTS 2022; 13:insects13030224. [PMID: 35323522 PMCID: PMC8955789 DOI: 10.3390/insects13030224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/18/2022] [Accepted: 02/23/2022] [Indexed: 11/29/2022]
Abstract
Analyzing the information-rich content of RNA can help uncover genetic events associated with social insect castes or other social polymorphisms. Here, we exploit a series of cDNA libraries previously derived from whole-body tissue of different castes as well as from three behaviourally distinct populations of the Eastern subterranean termite Reticulitermes flavipes. We found that the number (~0.5 M) of single nucleotide variants (SNVs) was roughly equal between nymph, worker and soldier caste libraries, but dN/dS (ratio of nonsynonymous to synonymous substitutions) analysis suggested that some of these variants confer a caste-specific advantage. Specifically, the dN/dS ratio was high (~4.3) for genes expressed in the defensively specialized soldier caste, relative to genes expressed by other castes (~1.7−1.8) and regardless of the North American population (Toronto, Raleigh, Boston) from which the castes were sampled. The populations, meanwhile, did show a large difference in SNV count but not in the manner expected from known demographic and behavioural differences; the highly invasive unicolonial population from Toronto was not the least diverse and did not show any other unique substitution patterns, suggesting any past bottleneck associated with invasion or with current unicoloniality has become obscured at the RNA level. Our study raises two important hypotheses relevant to termite sociobiology. First, the positive selection (dN/dS > 1) inferred for soldier-biased genes is presumably indirect and of the type mediated through kin selection, and second, the behavioural changes that accompany some social insect urban invasions (i.e., ‘unicoloniality’) may be detached from the loss-of-diversity expected from invasion bottlenecks.
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5
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Steward RA, de Jong MA, Oostra V, Wheat CW. Alternative splicing in seasonal plasticity and the potential for adaptation to environmental change. Nat Commun 2022; 13:755. [PMID: 35136048 PMCID: PMC8825856 DOI: 10.1038/s41467-022-28306-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 01/19/2022] [Indexed: 12/15/2022] Open
Abstract
Seasonal plasticity is accomplished via tightly regulated developmental cascades that translate environmental cues into trait changes. Little is known about how alternative splicing and other posttranscriptional molecular mechanisms contribute to plasticity or how these mechanisms impact how plasticity evolves. Here, we use transcriptomic and genomic data from the butterfly Bicyclus anynana, a model system for seasonal plasticity, to compare the extent of differential expression and splicing and test how these axes of transcriptional plasticity differ in their potential for evolutionary change. Between seasonal morphs, we find that differential splicing affects a smaller but functionally unique set of genes compared to differential expression. Further, we find strong support for the novel hypothesis that spliced genes are more susceptible than differentially expressed genes to erosion of genetic variation due to selection on seasonal plasticity. Our results suggest that splicing plasticity is especially likely to experience genetic constraints that could affect the potential of wild populations to respond to rapidly changing environments. Little is known about how alternative splicing and other post-transcriptional molecular mechanisms impact plasticity. Steward et al. use transcriptomic and genomic data from the butterfly Bicyclus anynana, finding that splicing plasticity is likely to experience genetic constraints.
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Affiliation(s)
| | | | - Vicencio Oostra
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
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6
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Harrison MC, Chernyshova AM, Thompson GJ. No obvious transcriptome-wide signature of indirect selection in termites. J Evol Biol 2020; 34:403-415. [PMID: 33290587 DOI: 10.1111/jeb.13749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/16/2020] [Accepted: 11/30/2020] [Indexed: 11/26/2022]
Abstract
The evolution of sterile helper castes in social insects implies selection on genes that underlie variation in this nonreproductive phenotype. These focal genes confer no direct fitness and are presumed to evolve through indirect fitness effects on the helper's reproducing relatives. This separation of a gene's phenotypic effect on one caste and its fitness effect on another suggests that genes for this and other forms of reproductive altruism are buffered from selection and will thus evolve closer to the neutral rate than genes directly selected for selfish reproduction. We test this hypothesis by comparing the strength of selection at loci associated in their expression with reproductive versus sterile castes in termites. Specifically, we gather caste-biased gene expression data from four termite transcriptomes and measure the global dN/dS ratio across gene sets and phylogenetic lineages. We find that the majority of examined orthologous gene groups show patterns of nucleotide substitution that are consistent with strong purifying selection and display little evidence for distinct signatures of direct versus indirect selection in reproductive and sterile castes. For one particular species (Reticulitermes flavipes), the strength of purifying selection is relaxed in a reproductive nymph-biased gene set, which opposes the nearly neutral idea. In other species, the synonymous rate (dS) alone was often found to be the highest in the sterile worker caste, suggesting a more subtle signature of indirect selection or an altogether different relationship between caste-biased expression and rates of molecular evolution.
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Affiliation(s)
- Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
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7
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Collet J, Fellous S. Do traits separated by metamorphosis evolve independently? Concepts and methods. Proc Biol Sci 2020; 286:20190445. [PMID: 30966980 DOI: 10.1098/rspb.2019.0445] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Despite the ubiquity of complex life cycles, we know little of the evolutionary constraints exerted by metamorphosis. Here, we present pitfalls and methods to answer whether animals with a complex life cycle can independently adapt to the environments encountered at each life stage, with a specific focus on the microevolution of quantitative characters. We first discuss challenges associated with study traits and populations. We further emphasize the benefits of using a combination of approaches. We then develop how multivariate methods can limit several issues by revealing genetic patterns that are invisible when only considering trait-by-trait genetic correlations. Finally, we detail how Lande's work on sexual dimorphism can be applied in measuring G matrices across life stages. The methods and tools described here will contribute towards building a predictive framework for trait evolution across life stages.
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Affiliation(s)
- Julie Collet
- 1 CBGP, INRA, CIRAD, IRD, Montpellier SupAgro, Univ. Montpellier , Montpellier , France.,2 CEFE, CNRS, Univ. Montpellier, Univ. Paul Valéry Montpellier 3, EPHE, IRD , Montpellier , France
| | - Simon Fellous
- 1 CBGP, INRA, CIRAD, IRD, Montpellier SupAgro, Univ. Montpellier , Montpellier , France
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8
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Core transcriptional signatures of phase change in the migratory locust. Protein Cell 2019; 10:883-901. [PMID: 31292921 PMCID: PMC6881432 DOI: 10.1007/s13238-019-0648-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/17/2019] [Indexed: 01/21/2023] Open
Abstract
Phenotypic plasticity plays fundamental roles in successful adaptation of animals in response to environmental variations. Here, to reveal the transcriptome reprogramming in locust phase change, a typical phenotypic plasticity, we conducted a comprehensive analysis of multiple phase-related transcriptomic datasets of the migratory locust. We defined PhaseCore genes according to their contribution to phase differentiation by the adjustment for confounding principal components analysis algorithm (AC-PCA). Compared with other genes, PhaseCore genes predicted phase status with over 87.5% accuracy and displayed more unique gene attributes including the faster evolution rate, higher CpG content and higher specific expression level. Then, we identified 20 transcription factors (TFs) named PhaseCoreTF genes that are associated with the regulation of PhaseCore genes. Finally, we experimentally verified the regulatory roles of three representative TFs (Hr4, Hr46, and grh) in phase change by RNAi. Our findings revealed that core transcriptional signatures are involved in the global regulation of locust phase changes, suggesting a potential common mechanism underlying phenotypic plasticity in insects. The expression and network data are accessible in an online resource called LocustMine (http://www.locustmine.org:8080/locustmine).
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9
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Warner MR, Qiu L, Holmes MJ, Mikheyev AS, Linksvayer TA. Convergent eusocial evolution is based on a shared reproductive groundplan plus lineage-specific plastic genes. Nat Commun 2019; 10:2651. [PMID: 31201311 PMCID: PMC6570765 DOI: 10.1038/s41467-019-10546-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 05/14/2019] [Indexed: 12/31/2022] Open
Abstract
Eusociality has convergently evolved multiple times, but the genomic basis of caste-based division of labor and degree to which independent origins of eusociality have utilized common genes remain largely unknown. Here we characterize caste-specific transcriptomic profiles across development and adult body segments from pharaoh ants (Monomorium pharaonis) and honey bees (Apis mellifera), representing two independent origins of eusociality. We identify a substantial shared core of genes upregulated in the abdomens of queen ants and honey bees that also tends to be upregulated in mated female flies, suggesting that these genes are part of a conserved insect reproductive groundplan. Outside of this shared groundplan, few genes are differentially expressed in common. Instead, the majority of the thousands of caste-associated genes are plastically expressed, rapidly evolving, and relatively evolutionarily young. These results emphasize that the recruitment of both highly conserved and lineage-specific genes underlie the convergent evolution of novel traits such as eusociality. Eusocial caste systems have evolved independently multiple times. Here, Warner et al. investigate the amount of shared vs. lineage-specific genes involved in the evolution of caste in pharaoh ants and honey bees by comparing transcriptomes across tissues, developmental stages, and castes.
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Affiliation(s)
| | - Lijun Qiu
- Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan
| | - Michael J Holmes
- Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan.,School of Life and Environmental Science, University of Sydney, Sydney, 2006, Australia
| | - Alexander S Mikheyev
- Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan.,Research School of Biology, Australian National University, Canberra, 0200, Australia
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10
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Warner MR, Mikheyev AS, Linksvayer TA. Transcriptomic basis and evolution of the ant nurse-larval social interactome. PLoS Genet 2019; 15:e1008156. [PMID: 31107868 DOI: 10.1101/514356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 05/31/2019] [Accepted: 04/24/2019] [Indexed: 05/20/2023] Open
Abstract
Development is often strongly regulated by interactions among close relatives, but the underlying molecular mechanisms are largely unknown. In eusocial insects, interactions between caregiving worker nurses and larvae regulate larval development and resultant adult phenotypes. Here, we begin to characterize the social interactome regulating ant larval development by collecting and sequencing the transcriptomes of interacting nurses and larvae across time. We find that the majority of nurse and larval transcriptomes exhibit parallel expression dynamics across larval development. We leverage this widespread nurse-larva gene co-expression to infer putative social gene regulatory networks acting between nurses and larvae. Genes with the strongest inferred social effects tend to be peripheral elements of within-tissue regulatory networks and are often known to encode secreted proteins. This includes interesting candidates such as the nurse-expressed giant-lens, which may influence larval epidermal growth factor signaling, a pathway known to influence various aspects of insect development. Finally, we find that genes with the strongest signatures of social regulation tend to experience relaxed selective constraint and are evolutionarily young. Overall, our study provides a first glimpse into the molecular and evolutionary features of the social mechanisms that regulate all aspects of social life.
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Affiliation(s)
- Michael R Warner
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alexander S Mikheyev
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Timothy A Linksvayer
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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11
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Warner MR, Mikheyev AS, Linksvayer TA. Transcriptomic basis and evolution of the ant nurse-larval social interactome. PLoS Genet 2019; 15:e1008156. [PMID: 31107868 PMCID: PMC6544314 DOI: 10.1371/journal.pgen.1008156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 05/31/2019] [Accepted: 04/24/2019] [Indexed: 12/13/2022] Open
Abstract
Development is often strongly regulated by interactions among close relatives, but the underlying molecular mechanisms are largely unknown. In eusocial insects, interactions between caregiving worker nurses and larvae regulate larval development and resultant adult phenotypes. Here, we begin to characterize the social interactome regulating ant larval development by collecting and sequencing the transcriptomes of interacting nurses and larvae across time. We find that the majority of nurse and larval transcriptomes exhibit parallel expression dynamics across larval development. We leverage this widespread nurse-larva gene co-expression to infer putative social gene regulatory networks acting between nurses and larvae. Genes with the strongest inferred social effects tend to be peripheral elements of within-tissue regulatory networks and are often known to encode secreted proteins. This includes interesting candidates such as the nurse-expressed giant-lens, which may influence larval epidermal growth factor signaling, a pathway known to influence various aspects of insect development. Finally, we find that genes with the strongest signatures of social regulation tend to experience relaxed selective constraint and are evolutionarily young. Overall, our study provides a first glimpse into the molecular and evolutionary features of the social mechanisms that regulate all aspects of social life.
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Affiliation(s)
- Michael R. Warner
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alexander S. Mikheyev
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Timothy A. Linksvayer
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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12
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Pauletto M, Manousaki T, Ferraresso S, Babbucci M, Tsakogiannis A, Louro B, Vitulo N, Quoc VH, Carraro R, Bertotto D, Franch R, Maroso F, Aslam ML, Sonesson AK, Simionati B, Malacrida G, Cestaro A, Caberlotto S, Sarropoulou E, Mylonas CC, Power DM, Patarnello T, Canario AVM, Tsigenopoulos C, Bargelloni L. Genomic analysis of Sparus aurata reveals the evolutionary dynamics of sex-biased genes in a sequential hermaphrodite fish. Commun Biol 2018; 1:119. [PMID: 30271999 PMCID: PMC6123679 DOI: 10.1038/s42003-018-0122-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 07/27/2018] [Indexed: 12/13/2022] Open
Abstract
Sexual dimorphism is a fascinating subject in evolutionary biology and mostly results from sex-biased expression of genes, which have been shown to evolve faster in gonochoristic species. We report here genome and sex-specific transcriptome sequencing of Sparus aurata, a sequential hermaphrodite fish. Evolutionary comparative analysis reveals that sex-biased genes in S. aurata are similar in number and function, but evolved following strikingly divergent patterns compared with gonochoristic species, showing overall slower rates because of stronger functional constraints. Fast evolution is observed only for highly ovary-biased genes due to female-specific patterns of selection that are related to the peculiar reproduction mode of S. aurata, first maturing as male, then as female. To our knowledge, these findings represent the first genome-wide analysis on sex-biased loci in a hermaphrodite vertebrate species, demonstrating how having two sexes in the same individual profoundly affects the fate of a large set of evolutionarily relevant genes.
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Affiliation(s)
- Marianna Pauletto
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Tereza Manousaki
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Serena Ferraresso
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Massimiliano Babbucci
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Alexandros Tsakogiannis
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Bruno Louro
- CCMAR-Centro de Ciências do Mar, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Nicola Vitulo
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Viet Ha Quoc
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Roberta Carraro
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Daniela Bertotto
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Rafaella Franch
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Francesco Maroso
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | | | | | | | | | - Alessandro Cestaro
- Research and Innovation Centre, Fondazione Edmund Mach, via Edmund Mach 1, 38010, San Michele all'Adige, Trento, Italy
| | - Stefano Caberlotto
- Valle Cà Zuliani Società Agricola Srl, Via Timavo 76, 34074, Monfalcone, Gorizia, Italy
| | - Elena Sarropoulou
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Costantinos C Mylonas
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Deborah M Power
- CCMAR-Centro de Ciências do Mar, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Tomaso Patarnello
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy
| | - Adelino V M Canario
- CCMAR-Centro de Ciências do Mar, University of Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Costas Tsigenopoulos
- Institute of Marine Biology, Biotechnology and Aquaculture ó, Hellenic Centre for Marine Research, Thalassocosmos, Former US Base at Gournes, 715 00, Heraklion, Greece
| | - Luca Bargelloni
- Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università, 16 35020, Legnaro, Italy.
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13
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Linkage mapping of yeast cross protection connects gene expression variation to a higher-order organismal trait. PLoS Genet 2018; 14:e1007335. [PMID: 29649251 PMCID: PMC5978988 DOI: 10.1371/journal.pgen.1007335] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 04/24/2018] [Accepted: 03/27/2018] [Indexed: 11/19/2022] Open
Abstract
Gene expression variation is extensive in nature, and is hypothesized to play a major role in shaping phenotypic diversity. However, connecting differences in gene expression across individuals to higher-order organismal traits is not trivial. In many cases, gene expression variation may be evolutionarily neutral, and in other cases expression variation may only affect phenotype under specific conditions. To understand connections between gene expression variation and stress defense phenotypes, we have been leveraging extensive natural variation in the gene expression response to acute ethanol in laboratory and wild Saccharomyces cerevisiae strains. Previous work found that the genetic architecture underlying these expression differences included dozens of “hotspot” loci that affected many transcripts in trans. In the present study, we provide new evidence that one of these expression QTL hotspot loci affects natural variation in one particular stress defense phenotype—ethanol-induced cross protection against severe doses of H2O2. A major causative polymorphism is in the heme-activated transcription factor Hap1p, which we show directly impacts cross protection, but not the basal H2O2 resistance of unstressed cells. This provides further support that distinct cellular mechanisms underlie basal and acquired stress resistance. We also show that Hap1p-dependent cross protection relies on novel regulation of cytosolic catalase T (Ctt1p) during ethanol stress in a wild oak strain. Because ethanol accumulation precedes aerobic respiration and accompanying reactive oxygen species formation, wild strains with the ability to anticipate impending oxidative stress would likely be at an advantage. This study highlights how strategically chosen traits that better correlate with gene expression changes can improve our power to identify novel connections between gene expression variation and higher-order organismal phenotypes. A major goal in genetics is to understand how individuals with different genetic makeups respond to their environment. Understanding these “gene-environment interactions” is important for the development of personalized medicine. For example, gene-environment interactions can explain why some people are more sensitive to certain drugs or are more likely to get certain cancers. While the underlying causes of gene-environment interactions are unclear, one possibility is that differences in gene expression across individuals are responsible. In this study, we examined that possibility using baker’s yeast as a model. We were interested in a phenomenon called acquired stress resistance, where cells exposed to a mild dose of one stress can become resistant to an otherwise lethal dose of severe stress. This response is observed in diverse organisms ranging from bacteria to humans, though the specific mechanisms governing acquisition of higher stress resistance are poorly understood. To understand the differences between yeast strains with and without the ability to acquire further stress resistance, we employed genetic mapping. We found that part of the variation in acquired stress resistance was due to sequence differences in a key regulatory protein, thus providing new insight into how different individuals respond to acute environmental change.
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Schultner E, Oettler J, Helanterä H. The Role of Brood in Eusocial Hymenoptera. QUARTERLY REVIEW OF BIOLOGY 2018; 92:39-78. [PMID: 29558609 DOI: 10.1086/690840] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Study of social traits in offspring traditionally reflects on interactions in simple family groups, with famous examples including parent-offspring conflict and sibling rivalry in birds and mammals. In contrast, studies of complex social groups such as the societies of ants, bees, and wasps focus mainly on adults and, in particular, on traits and interests of queens and workers. The social role of developing individuals in complex societies remains poorly understood. We attempt to fill this gap by illustrating that development in social Hymenoptera constitutes a crucial life stage with important consequences for the individual as well as the colony. We begin by describing the complex social regulatory network that modulates development in Hymenoptera societies. By highlighting the inclusive fitness interests of developing individuals, we show that they may differ from those of other colony members. We then demonstrate that offspring have evolved specialized traits that allow them to play a functional, cooperative role within colonies and give them the potential power to act toward increasing their inclusive fitness. We conclude by providing testable predictions for investigating the role of brood in colony interactions and giving a general outlook on what can be learned from studying offspring traits in hymenopteran societies.
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15
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Pennell TM, Holman L, Morrow EH, Field J. Building a new research framework for social evolution: intralocus caste antagonism. Biol Rev Camb Philos Soc 2018; 93:1251-1268. [PMID: 29341390 PMCID: PMC5896731 DOI: 10.1111/brv.12394] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/02/2023]
Abstract
The breeding and non‐breeding ‘castes’ of eusocial insects provide a striking example of role‐specific selection, where each caste maximises fitness through different morphological, behavioural and physiological trait values. Typically, queens are long‐lived egg‐layers, while workers are short‐lived, largely sterile foragers. Remarkably, the two castes are nevertheless produced by the same genome. The existence of inter‐caste genetic correlations is a neglected consequence of this shared genome, potentially hindering the evolution of caste dimorphism: alleles that increase the productivity of queens may decrease the productivity of workers and vice versa, such that each caste is prevented from reaching optimal trait values. A likely consequence of this ‘intralocus caste antagonism’ should be the maintenance of genetic variation for fitness and maladaptation within castes (termed ‘caste load’), analogous to the result of intralocus sexual antagonism. The aim of this review is to create a research framework for understanding caste antagonism, drawing in part upon conceptual similarities with sexual antagonism. By reviewing both the social insect and sexual antagonism literature, we highlight the current empirical evidence for caste antagonism, discuss social systems of interest, how antagonism might be resolved, and challenges for future research. We also introduce the idea that sexual and caste antagonism could interact, creating a three‐way antagonism over gene expression. This includes unpacking the implications of haplodiploidy for the outcome of this complex interaction.
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Affiliation(s)
- Tanya M Pennell
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Luke Holman
- School of Biosciences, University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Edward H Morrow
- Evolution Behaviour and Environment Group, School of Life Sciences, University of Sussex, Falmer, East Sussex, BN1 9QG, UK
| | - Jeremy Field
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
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16
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Lucas ER, Romiguier J, Keller L. Gene expression is more strongly influenced by age than caste in the ant Lasius niger. Mol Ecol 2017; 26:5058-5073. [DOI: 10.1111/mec.14256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/20/2017] [Accepted: 06/28/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Eric R. Lucas
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
- Department of Vector Biology; Liverpool School of Tropical Medicine; Liverpool UK
| | - Jonathan Romiguier
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
| | - Laurent Keller
- Department of Ecology and Evolution; Biophore, University of Lausanne; Lausanne Switzerland
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17
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Schrader L, Helanterä H, Oettler J. Accelerated Evolution of Developmentally Biased Genes in the Tetraphenic Ant Cardiocondyla obscurior. Mol Biol Evol 2017; 34:535-544. [PMID: 27999112 PMCID: PMC5400372 DOI: 10.1093/molbev/msw240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Plastic gene expression underlies phenotypic plasticity and plastically expressed genes evolve under different selection regimes compared with ubiquitously expressed genes. Social insects are well-suited models to elucidate the evolutionary dynamics of plastic genes for their genetically and environmentally induced discrete polymorphisms. Here, we study the evolution of plastically expressed genes in the ant Cardiocondyla obscurior—a species that produces two discrete male morphs in addition to the typical female polymorphism of workers and queens. Based on individual-level gene expression data from 28 early third instar larvae, we test whether the same evolutionary dynamics that pertain to plastically expressed genes in adults also pertain to genes with plastic expression during development. In order to quantify plasticity of gene expression over multiple contrasts, we develop a novel geometric measure. For genes expressed during development, we show that plasticity of expression is positively correlated with evolutionary rates. We furthermore find a strong correlation between expression plasticity and expression variation within morphs, suggesting a close link between active and passive plasticity of gene expression. Our results support the notion of relaxed selection and neutral processes as important drivers in the evolution of adaptive plasticity.
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Affiliation(s)
- Lukas Schrader
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany.,Centre for Social Evolution, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Heikki Helanterä
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Jan Oettler
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
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18
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Pespeni MH, Ladner JT, Moczek AP. Signals of selection in conditionally expressed genes in the diversification of three horned beetle species. J Evol Biol 2017; 30:1644-1657. [PMID: 28379613 DOI: 10.1111/jeb.13079] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 03/05/2017] [Indexed: 01/20/2023]
Abstract
Species radiations may be facilitated by phenotypic differences already present within populations, such as those arising through sex-specific development or developmental processes biased towards particular reproductive or trophic morphs. We sought to test this hypothesis by utilizing a comparative transcriptomic approach to contrast among- and within-species differentiation using three horned beetle species in the genus Onthophagus. These three species exhibit differences along three phenotypic axes reflective of much of the interspecific diversity present within the genus: horn location, polarity of sexual dimorphism and degree of nutritional sensitivity. Our approach combined de novo transcript assembly, assessment of amino acid substitutions (dN/dS) across orthologous gene pairs and integration of gene function and conditional gene expression data. We identified 17 genes across the three species pairs related to axis patterning, development and metabolism with dN/dS > 1 and detected elevated dN/dS in genes related to metabolism and biosynthesis in the most closely related species pair, which is characterized by a loss of nutritional polyphenism and a reversal of sexual dimorphism. Further, we found that genes that are conditionally expressed (i.e. as a function of sex, nutrition or body region) within one of our focal species also showed significantly stronger signals of positive or relaxed purifying selection between species divergent along the same morphological axis (i.e. polarity of sexual dimorphism, degree of nutritional sensitivity or location of horns). Our findings thus reveal a positive relationship between intraspecific differentiation due to condition-specific development and genetic divergences among species.
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Affiliation(s)
- M H Pespeni
- Department of Biology, Indiana University, Bloomington, IN, USA.,Department of Biology, University of Vermont, Burlington, VT, USA
| | - J T Ladner
- Center for Genome Sciences, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD, USA
| | - A P Moczek
- Department of Biology, Indiana University, Bloomington, IN, USA
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19
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Linksvayer TA, Wade MJ. Theoretical Predictions for Sociogenomic Data: The Effects of Kin Selection and Sex-Limited Expression on the Evolution of Social Insect Genomes. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00065] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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20
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Smith CR, Helms Cahan S, Kemena C, Brady SG, Yang W, Bornberg-Bauer E, Eriksson T, Gadau J, Helmkampf M, Gotzek D, Okamoto Miyakawa M, Suarez AV, Mikheyev A. How Do Genomes Create Novel Phenotypes? Insights from the Loss of the Worker Caste in Ant Social Parasites. Mol Biol Evol 2015; 32:2919-31. [PMID: 26226984 PMCID: PMC4651238 DOI: 10.1093/molbev/msv165] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A central goal of biology is to uncover the genetic basis for the origin of new
phenotypes. A particularly effective approach is to examine the genomic
architecture of species that have secondarily lost a phenotype with respect to
their close relatives. In the eusocial Hymenoptera, queens and workers have
divergent phenotypes that may be produced via either expression of alternative
sets of caste-specific genes and pathways or differences in expression patterns
of a shared set of multifunctional genes. To distinguish between these two
hypotheses, we investigated how secondary loss of the worker phenotype in
workerless ant social parasites impacted genome evolution across two independent
origins of social parasitism in the ant genera Pogonomyrmex and
Vollenhovia. We sequenced the genomes of three social
parasites and their most-closely related eusocial host species and compared gene
losses in social parasites with gene expression differences between host queens
and workers. Virtually all annotated genes were expressed to some degree in both
castes of the host, with most shifting in queen-worker bias across developmental
stages. As a result, despite >1 My of divergence from the last common
ancestor that had workers, the social parasites showed strikingly little
evidence of gene loss, damaging mutations, or shifts in selection regime
resulting from loss of the worker caste. This suggests that regulatory changes
within a multifunctional genome, rather than sequence differences, have played a
predominant role in the evolution of social parasitism, and perhaps also in the
many gains and losses of phenotypes in the social insects.
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Affiliation(s)
| | | | - Carsten Kemena
- Institute for Evolution and Biodiversity, Westfälische Wilhems-Universität Münster, Münster, Germany
| | - Seán G Brady
- Department of Entomology, National Museum of Natural History, Smithsonian Institution, Washington DC
| | - Wei Yang
- Department of Computer Science, University of Illinois Urbana-Champaign
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, Westfälische Wilhems-Universität Münster, Münster, Germany
| | - Ti Eriksson
- School of Life Sciences, Arizona State University
| | | | | | - Dietrich Gotzek
- Department of Entomology, University of Georgia Department of Animal Biology, University of Illinois Urbana-Champaign
| | - Misato Okamoto Miyakawa
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan
| | - Andrew V Suarez
- Department of Animal Biology, University of Illinois Urbana-Champaign Department of Entomology, University of Illinois Urbana-Champaign
| | - Alexander Mikheyev
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology, Onna, Okinawa, Japan
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21
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Ruden DM, Cingolani PE, Sen A, Qu W, Wang L, Senut MC, Garfinkel MD, Sollars VE, Lu X. Epigenetics as an answer to Darwin's "special difficulty," Part 2: natural selection of metastable epialleles in honeybee castes. Front Genet 2015; 6:60. [PMID: 25759717 PMCID: PMC4338822 DOI: 10.3389/fgene.2015.00060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 02/08/2015] [Indexed: 11/15/2022] Open
Abstract
In a recent perspective in this journal, Herb (2014) discussed how epigenetics is a possible mechanism to circumvent Charles Darwin's "special difficulty" in using natural selection to explain the existence of the sterile-fertile dimorphism in eusocial insects. Darwin's classic book "On the Origin of Species by Means of Natural Selection" explains how natural selection of the fittest individuals in a population can allow a species to adapt to a novel or changing environment. However, in bees and other eusocial insects, such as ants and termites, there exist two or more castes of genetically similar females, from fertile queens to multiple sub-castes of sterile workers, with vastly different phenotypes, lifespans, and behaviors. This necessitates the selection of groups (or kin) rather than individuals in the evolution of honeybee hives, but group and kin selection theories of evolution are controversial and mechanistically uncertain. Also, group selection would seem to be prohibitively inefficient because the effective population size of a colony is reduced from thousands to a single breeding queen. In this follow-up perspective, we elaborate on possible mechanisms for how a combination of both epigenetics, specifically, the selection of metastable epialleles, and genetics, the selection of mutations generated by the selected metastable epialleles, allows for a combined means for selection amongst the fertile members of a species to increase colony fitness. This "intra-caste evolution" hypothesis is a variation of the epigenetic directed genetic error hypothesis, which proposes that selected metastable epialleles increase genetic variability by directing mutations specifically to the epialleles. Natural selection of random metastable epialleles followed by a second round of natural selection of random mutations generated by the metastable epialleles would allow a way around the small effective population size of eusocial insects.
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Affiliation(s)
- Douglas M. Ruden
- Department of Obstetrics and Gynecology, C. S. Mott Center for Human Growth and Development and Center for Urban Responses to Environmental Stressors, Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Pablo E. Cingolani
- School of Computer Science and Genome Quebec Innovation Centre, McGill UniversityMontreal, QC, Canada
| | - Arko Sen
- Department of Pharmacology, Wayne State UniversityDetroit, MI, USA
| | - Wen Qu
- Department of Pharmacology, Wayne State UniversityDetroit, MI, USA
| | - Luan Wang
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Marie-Claude Senut
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
| | - Mark D. Garfinkel
- Department of Biological Sciences, University of Alabama in HuntsvilleHuntsville, AL, USA
| | - Vincent E. Sollars
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall UniversityHuntington, WV, USA
| | - Xiangyi Lu
- Institute of Environmental Health Sciences, Wayne State UniversityDetroit, MI, USA
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